In nutrient limited ecosystems, bacteria have a marked tendency to adhere to surfaces and initiate the formation of a biofilm. A biofilm is a community of microbes, embedded in an organic polymer matrix, adhering to a surface. In nutrient limited natural and industrial ecosystems biofilm cells will predominate and cause problems as increased frictional resistence to fluids in water conduits and on ship hulls (fouling), decreased heat transfer from heat exchangers, corrosion of metallic substrata and contamination in the food and biotechnology industry. Biofilms are also a severe problem in medical science and industry acusing dental plaque, contaminated endoscopes and contact lenses, prosthetic device colonisation and biofilm formation on medical implants.
The biofilm matrix is a collection of microcolonies with water channels in between and an assortment of cells and extracellular polymers (polysaccharides, glycoproteins, proteins). Bacterial extracellular polysaccharides are composed of homo- and heteropolysaccharides of particularly glucose, fucose, mannose, galactose, fructose, pyruvate, mannuronic acid or glucuronic acid based complexes. The different bonds between the saccharides give rise to a multitude of different polysaccharides including levans, polymannans, dextrans, cellulose, amylopectin, glycogen and alginate.
Bacteria growing in biofilms are more resistant to antibiotics and disinfectants than planktonic cells and the resistance increases with the age of the biofilm. Bacterial biofilm also exhibits increased physical resistance towards desiccation, extreme temperatures or light. As mentioned, biofilm formation causes industrial, environmental and medical problems and the difficulties in cleaning and disinfection of bacterial biofilm with chemicals is a major concern in many industries. Furthermore, the trend towards milder disinfection and cleaning compositions may increase the insufficient cleaning of surfaces covered with biofilm.
The object of present invention is to provide an efficient and environmentally safe method for eliminating biofilm and living bacterial cells present on a surface.